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Yale researchers establish link between plant evolution and drought resistance

BY SELIN NALBANTOGLU STAFF REPORTER

Plants with more complex water transport structures are more resistant to drought conditions, making them more likely to survive and pass this characteristic on to their offspring.

That’s the conclusion Yale researchers have reached after poring over the fossil records of ancient plants that span tens of millions of years.

Earlier this month, a group of University affiliates working with faculty from Bates College, the University of Maine and Haverford College, among other institutions, published a paper on identifying the impact of droughts and drought resistance in determining plant structure over time.

“This study is an excellent example of how a collaborative, multidisciplinary approach can yield novel insights into evolutionary questions,” Jonathan Wilson, an associate professor of environmental studies at Haverford College and an author on the paper, wrote in an email to the News. “Bringing together modeling, physiology and paleontology and integrating their data and methods shed a great deal of light on this period in plant evolution.”

Lead author Martin Bouda GRD ’17, a researcher at the Institute of Botany at the Czech Academy of Sciences, studies the network properties of plant parts such as root systems and how these systems affect water intake of plants. In this paper, he was responsible for conceptualizing the water transport within the plants and building computational models to analyze these hydraulic processes. Craig Brodersen, a professor of plant physiological ecology at the Yale School of the Environment, was the principal investigator for the paper.

According to Brodersen, this new research stems from his team’s previous work on drought tolerance in plants such as grapevines. Previously, they have used new imaging techniques to study the vascular systems of various plants and the effects of different vascular organization on plant survival in droughts.

Brodersen explained that during extreme drought conditions, plants may accumulate air bubbles in their vascular systems.

“These bubbles block the flow of water from the roots to the leaves,” Brodersen wrote in an email to the News. “One air bubble among the many hundreds to thousands of vessels in a plant might not cause too much harm initially, but these bubbles can spread between vessels wherever there is a connection to an adjacent one. Understanding how the vessel network of a plant is connected can then tell us something about how air bubbles spread, which becomes a greater problem during prolonged drought.”

The researchers used this framework as a guiding question to study the evolution of vascular plants over millions of years, according to Brodersen.

When conducting this research, the team of scientists referenced a collection of images put together over the past century by various paleobotanists. The images depicted xylems, a specialized tissue responsible for transporting water and nutrients, of extinct plants. The fossil record, which spanned approximately 50 million years, gave the researchers an understanding of the arrangement of various vascular systems in plants.

“In this particular case, some of our previous work on the very fine structure of a vessel network got me thinking of the big picture instead: our living plants almost all have a gap in the middle of the network, whereas in the earliest land plants, the network occupied a solid cylinder of tissue,” Bouda wrote in an email to the News. “I built a little simulation to see if embolism spread differently on the two different cross-sections. The results were encouraging and fit in well with Craig’s ongoing work on seedless vascular plants.”

While Brodersen produced the actual microscope images of the networks within the plants the

TIM TAI/PHOTOGRAPHY EDITOR

Yale faculty has helped in publication of a paper detailing plant structure in determining outcomes during drought conditions.

researchers were studying, Bouda constructed idealized, possible networks to use as comparison cases for the observed networks.

Then, Bouda added, the researchers worked with Wilson to study fossil plants and realized that the fossil plants’ networks were more vulnerable to droughts than those of present-day plants.

“[T]here’s a clear pattern of xylem network shapes starting out with simple forms and becoming more complex,” Brodersen wrote. “Using the arrangement of the conduits within those vessel networks we were able to map out the possble pathways that air bubbles could spread from conduit to conduit. We then compared networks from extinct plants to living relatives today such as ferns and lycophytes.”

Using a computer model, the researchers were able to simulate drought conditions and study the effects of those conditions on various xylem configurations. The results suggested that the xylems of the earliest plants, which were also the simplest in arrangement, were the most vulnerable to air bubbles during a drought. Plants with a more complicated vascular system outperformed other species during the drought, according to Brodersen.

This paper is the result of interdisciplinary collaboration of experts in mathematical modeling, plant anatomy and paleobotany. The researchers applied current plant water transport theory and experimental work to their own inquiry. Brodersen explained that the team at Yale, including Bouda, developed the computer model and anatomical observations used to test their hypothesis. He added that Wilson served as the paleobotanist who helped “guide the species selection from the fossil record.”

Brodersen explained that this research stems from his laboratory’s collaboration with the plant breeding community. The findings could potentially inform the development of more drought-resistant varieties of plants.

According to Bouda, this paper helps elucidate “something fundamental about the structure and function of vascular plants that has been overlooked for a long time.” While the practical applications of the research are not immediately apparent, Bouda hopes that the findings might help diminish the tradeoff between crop yield and drought resistance, which has traditionally been a problem in agriculture.

“I thoroughly enjoyed exploring the paleobotanical fossil record,” Bouda wrote. “A lot of this was completely new to me, and I daresay both Craig and I got pretty excited discovering the variety of vascular forms that evolution had tried out over 400 million or so years. In the end, we found that we had taken a roundabout way to broadly reconstruct the dataset used by F. O. Bower a hundred years ago to show that vascular complexity depends on plant size, and that’s when the final piece of the puzzle snapped into place.”

Xylem comes from the Greek word xylon, meaning wood.

Contact SELIN NALBANTOGLU at selin.nalbantoglu@yale.edu .

Yale undergraduates develop award-winning strategy to prevent gun violence

BY ABEL GELETA CONTRIBUTING REPORTER

Three Yale undergraduates developed a multi-pronged approach to address the gun violence epidemic in the United States through various community resources and entity synergies, winning the Tulane Health Policy Case Competition and highlighting the potential for combining a youth mentorship program and firearm safety training to mitigate gun violence.

Abe Baker-Butler ’25, Patryk Dabek ’25 and Allie Dettelbach ’25 had the winning plan for reducing firearm homicides among the 41 teams from 22 universities that participated in the THPPC. After analyzing the status quo of gun violence in Opelousas, Louisiana, they created a plan — called Operation Healthy Homefront, or OHH — that integrated an after-school mentoring program and firearms safety instruction led by veterans in these communities.

“Gun violence is such a pressing issue, and it is so under-addressed,” Baker-Butler said. “There are so many common sense solutions attracting broad-based support. We’re happy knowing that we’ve been able to make at least some addition to the policy discussion around gun safety with our proposal, but we’re not done yet.”

The idea focuses on involving at-risk youth and veterans in the strategic development of a viable solution for communities with a high incidence of deaths or injuries from a firearm, while also serving as a mutually beneficial program aimed at providing essential skills and opportunities to youth and employment opportunities for veterans.

Baker-Butler described how his earlier experience with public health work tackling substance abuse in his high school and trying to provide accessible healthcare to low-income senior citizens inspired him to compete in this event. All team members

COURTESY OF SAM RIFKIND-BROWN

Yale students place first for their proposal for reducing gun violence in communities at the Tulane Health Policy Case Competition.

combined their interests in policy-making, public health and healthcare to produce a novel solution to a pervasive problem in the United States.

The strong collaboration between the three teammates in this competition allowed them to capitalize on each other’s skills and use the competition to gain new knowledge and create something of long-lasting impact.

Dettelbach noted how the team “wanted to think about how [they] could address that problem from a public health angle but also an angle of political feasibility.” This case competition allowed participants to analyze the multiple levels of government to devise solutions that would withstand the political obstacles to reducing gun violence in the United States.

He argued that numerous stakeholders must collaborate to commit enough resources and efforts toward reasonable, effective and sustainable attempts to mitigate the issues diverse populations face.

“We all learned about the policy-making bodies at each of those levels and the organizations that exist at those levels that we can harness to come to this final proposal,” said Dettelbach.

Dabek, along with Butler-Baker. initially brought up the idea to enter this competition with Dettelbach after hearing about it from Howard Foreman, Professor of Diagnostic Radiology, Economics, and Public Health. Dabek spent his summer delivering healthcare as an EMT and establishing a non-profit to improve health conditions in war-ravaged Ukraine. In light of his summer experiences, he evaluated the public health issues plaguing the United States and accepted the opportunity to participate in this competition.

To comprehend how to advocate for social justice and health equity effectively, Dabek emphasized the importance of policy formation in implementing health equity in diverse communities.

Beyond policy proposal and implementation, all team members highlighted the need to collaborate closely with those communities they look to serve with this plan. Dabek said this proposal was only one step in developing the muchneeded solution to gun violence.

“We don’t forget about the people that we’re actually serving and the issues they’re dealing with, and we want to ensure we are in contact with the community and see what the community has to say,” said Dabek.

Baker-Butler recognized that the team is grateful to have won and received recognition from the judges. Still, he said, the solution to the gun violence epidemic requires numerous people to continue thinking and coming up with potential ideas to solve this problem.

Foreman encouraged his students in his Health Economics and Policy course to participate in this competition because the THPCC “was perfectly aligned with the mission of the class” which aims to “prepare students to critically think about actual challenges in society.” In many cases, Foreman stated, individuals might propose policy solutions and ideas that are “juvenile and naive” and make various suggestions and solutions that are not feasible in implementation.

Foreman highlighted the thoughtful and detailed nature of this team’s proposal.

“Every measure [for judging] that I’d look at … either passed or far exceeded my expectations,” said Foreman. “My expectation for a proposal of this type is to see something that agrees with the law; It’s not basically imagining a world where certain laws don’t exist … It’s not going to demand such enormous resources to be out of the scope of the problem.”

Foreman expressed his desire to witness this proposal be piloted on a small scale, improved and then scaled further to accommodate and assist vulnerable populations. In many ways, these are how programs are kick-started and implemented nationally.

Foreman believes that the students’ passion for this issue, coupled with the ability to gain enough attention and support, could be the catalyst for this proposal to be implemented effectively.

The presentation the winners presented to judges can be viewed at this link.

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Yale researchers explore potential benefi ts and risks of telehealth

BY JUAN VELASCO CONTRIBUTING REPORTER

In 2021, about 37 percent of adults in the United States had used telehealth in the prior 12 months, according to the National Center of Health Statistics.

In a paper published on Nov. 30, an assistant Yale professor and two associate Yale professors analyzed the potential opportunities and pitfalls of telehealth, and also provided suggestions for promoting high-quality, equitable and ethical use of it. The study analyzed three ethical considerations: distributive justice, unintended consequences, and autonomy versus benefi cence. Among the benefi ts highlighted by the authors was the increased availability of options for patients.

However, it was also emphasized that there is a risk that telehealth could undermine the quality of care for patients with certain conditions such as valvular disease, among others.

“Cognitive bias may lead many of us to view technological advances as inherently good or positive,” Sarah C. Hull, one of the study’s authors said. “While the intent of telehealth to provide greater convenience and access to patients is certainly laudable, it is important to interrogate the potential impacts of inferior quality or unintended consequences, particularly with respect to vulnerable populations.”

Hull, a Yale assistant professor of cardiology, wrote the study alongside Joyce Oen-Hsiao, associate professor of clinical medicine and director of Cardiac Rehabilitation Services at the Yale-New Haven Hospital Heart & Vascular Center, and Erica S. Spatz, Yale associate professor of cardiology.

It has been documented by the National Center for Health Statistics, part of the Centers for Disease Control and Prevention, that the use of telehealth is correlated with the degree of urbanization. The authors noted in the paper that telehealth could increase disparities in populations with limited digital access.

To improve the use of telehealth, the authors provided some recommendations, such as incorporat-

CATE ROSER/STAFF ILLUSTRATOR

Yale cardiologists analyzed the practical and ethical considerations of telehealth.

ing remote digital diagnostic devices and training patients how to use them. Additionally, it was suggested that the use of this method to deliver health-related services could be used as a complement to, rather than a replacement for, face-to-face visits.

Harlan Krumholz — Harold H. Hines, Jr. Professor of Medicine, Professor in the Institute for Social and Policy Studies of Investigative Medicine and of Public Health, and director of the Yale New Haven Hospital Center for Outcomes Research and Evaluation — agreed.

“The potential of telehealth is immense, as we confi gure a system that more fully delivers care when and where the patient prefers, and obviates the inconveniences of the traditional approach,” Krumholz said. “As we embark on this new era, we need to be attentive to how to do telehealth well, cognizant that we do not have the many advantages of seeing a patient in person and employing strategies that minimize the chances that something important has been missed.”

According to Makoto Mori, an Integrated Cardiothoracic Surgery Resident at Yale, the potential of telehealth has been realized in clinical encounters, such as outpatient visits and postoperative follow-up, especially with patients who live far from the hospital. Regarding physiologic monitoring through the uses of telehealth, he explained that “remote physiologic monitoring (vitals, activity level, etc) has a lot of potential in improving post-acute phase of care but the benefi t has not been largely realized outside of the research context.”

Mori also noted a potential risk of telehealth. “It does take away the in-person face-to-face encounters that are often central to physician-patient relationships,” Mori said. “So it needs to be used judiciously. Important conversations like pre-surgical counseling and visits for patients who are struggling in their clinical course are something that telehealth should not replace.”

According to Hull, the team aims for this study to help foster the evaluation of the benefi ts and drawbacks of telehealth. She hopes “that our ethical analysis will encourage further research to elucidate both the advantages and limitations of telehealth such that it can be deployed in a thoughtful and evidence-based framework.”

The study was featured in the Yale Journal of Biology and Medicine.

Contact JUAN VELASCO at juan.velasco@yale.edu .

Study on northern treeshrews reveals e ects of climate change

BY JAMES STEELE CONTRIBUTING REPORTER

Research findings on the evolution of northern treeshrews, a small species of mammal, contradict two of the most widely tested and accepted ecogeographical rules.

A study published on Nov. 29 analyzed the northern treeshrew’s evolution over the past 130 years, looking at what it reveals about two major ecogeographical rules: the island rule and Bergmann’s rule.

The island rule describes the tendency for small mammal species to evolve larger body sizes and for large mammal species to evolve smaller body sizes as they migrate to islands. Bergmann’s rule examines the e ects of temperature on body size, stating that animals in environments of higher latitudes with lower temperatures will evolve to have larger than average body sizes relative to other members of their species. Conversely, species in lower latitudes and warmer climates will evolve smaller body sizes.

“This, to my knowledge, is the first time that [a study] shows a change, not just in a slope or strength of [the island rule or Bergmann’s rule], but in a direction,” Virginie Millien said.

Millien, an associate professor at McGill University, was one of the co-authors of the paper. The paper was written by lead author Maya Juman ’20, with co-authors Eric J. Sargis, professor of anthropology, archaeological studies, ecology and evolutionary biology at the School of the Environment; Link E. Olson, a curatorial affiliate in mammalogy at the Yale Peabody Museum and associate professor in the Department of Biology and Wildlife at the University of Alaska; and Millien.

According to Juman, fi nding cases in which a particular species breaks these ecogeographical rules is not new.

However, discovering the breakage of a rule over time has never been done before. The results of this study show not just a simple breakage of ecogeographical rules, but a trend towards rule reversal over time.

“What’s unique about [our study] is that we show that same opposite pattern, but we also include time as an element,” Juman said.

The researchers examined 839 different specimens collected over the span of 130 years. The study found that the evolutionary behavior of the northern treeshrew directly contradicted Bergmann’s rule, with treeshrew body sizes decreasing in colder climates farther away from the equator.

In addition, island-dwelling treeshrews were found to adhere to Bergmann’s rule while mainland treeshrews did not. As a result, the team determined that the island rule is maintained at higher altitudes but is broken in latitudes closer to the equator.

“Frankly, I think rules are never always true, but I think this is casting more doubt on them,” Juman said.

According to Juman, for treeshrews, it is possible for a measurable change in body size to form over the course of just 130 years. Juman noted that this is because treeshrew generations form in about one year. This short time between generations allows for much faster natural selection and adaptation to occur.

Additionally, the research team’s method of body measurement aided their ability to discern change in size. Only the treeshrews’ skeletons and skins were available to survey, so the researchers used the size of the treeshrew skulls as a proxy for the true body size of the animal.

Juman also noted how these findings may be attributable to climate change. According to Juman, climate change is affecting scientists’ understanding of the island rule and Bergmann’s rule because climate change impacts temperature and affects different latitudes in different ways. Over time, the ability to generalize the evolutionary trends of species with these

JOY LIAN/CONTRIBUTING ILLUSTRATOR

A recently published study details the evolutionary breakage of ecogeographical rules as climate change progresses.

rules may degrade, and scientists’ “reliance on these rules” might need to be “revisited over time as climate change ramps up,” Juman said.

“What else [other than global warming] could have triggered the reversal [of ecogeographical rules]? … It’s the most sensible explanation,” Millien said.

Though the researchers did not explicitly prove that climate change caused the reversal of these two ecogeographical rules, the data found in the study regarding the body size changes also correlates with a rise in the effects of global warming.

According to Millien, the rate at which Bergmann’s rule was reversed noticeably increased after the Industrial Revolution. The rate has accelerated even more sharply over the past couple decades.

The researchers also highlighted how crucial museum collections were towards their research. The data set they analyzed included specimens from sixteen different museums. Without such collections, the researchers recognized that the scientific research would be severely stifled.

“This particular species happens to be the best represented in museum collections … We were lucky to have such an extensive series, both temporally and spatially,” Olson wrote.

The study was published in the journal Scientific Reports.